Any sort of second step verification that a business is more than just a front. Or even just watching out for things like this HN post and aggressively cleaning house when this stuff comes up (and actively banning merchants that try the same trick).
Heck, they could even do something like twitters blue checkmark with their goods. For untrusted sources, keep their supplies in quarantined from the trusted sources and start vetting suppliers (check on where they are at, if they've got a history of selling fake goods, checking into the goods they are selling to ensure they are legitimate). Once a supplier passes that test, then move their goods in with the trusted sources.
Really, just about anything would make amazon more reliable and less scammy.
